Is it advisable to use keg lub on the bung when fitting it on the immersion rod and a Corny keg lid?
It seems like a bit of hit a miss to get the correct hight fit in this specific use case especially on Corny kegs with double ABS top handles.
If it's a spacing issue, I'd recommend picking up a few extra stoppers to act as spacers. The will provide enough clearance so the unit sits above the latch.
What about the question about keg lub on the inside of the bung?